College of Agriculture & Natural Resources (COANRE)
http://localhost/xmlui/handle/123456789/1292
2024-03-29T12:50:20ZCharacterization, Awareness of Products, and Technical Efficiency of Baobab Candy Retailing in Kenya
http://localhost/xmlui/handle/123456789/6248
Characterization, Awareness of Products, and Technical Efficiency of Baobab Candy Retailing in Kenya
Kinyili, Mutua
Globally, baobab tree is among the leading Indigenous Fruit Trees (IFTs) with extensive benefits such as a source of nutritious food, income, and raw materials in food processing. The tree grows in harsh climatic conditions where crop production is difficult. Despite the great importance of baobab, the tree remains underutilized and its market operates informally through weak value chains and few market players. Retail sector plays a crucial role in economic development and represents the largest proportion among agricultural value chain actors. However, baobab products remain few in the retail markets. Baobab candy is the common traded product by retailers in Kenya. Moreover, there exist knowledge gap regarding baobab retailing. Hence, this study sought to characterize baobab candy retailers, establish their awareness levels of baobab products, and estimate the technical efficiency (TE) of candy enterprises in the rural township and urban markets. The study adopted purposive and cluster sampling designs to draw a random sample of 352 respondents. A structured questionnaire was used for data collection. Multivariate statistical technique of principal component analysis (PCA) and cluster analysis (CA) was used to characterize candy retailers. A zero-truncated poison (ZTP) model was used to assess the determinants of retailer awareness toward baobab products. While Data envelopment analysis (DEA) and Tobit models were employed to establish the level of TE and its determinant respectively. The study results revealed that candy retailers are heterogeneous in nature and can be classified into three clusters namely: low-volume, average-volume, and high-volume retailers. Descriptive statistics indicated a low product awareness across the markets (mean=10) from a list of 28 products. ZTP model showed that gender, age, education level, years of retailing, and group membership significantly influenced retailers’ awareness positively whereas, distance to the market and income from other sources had a negative influence on awareness. DEA results indicated that candy enterprises attained a TE score of 0.69 in constant return to scale and 0.85 in variable return to scale. The model also revealed that majority of candy enterprises (94%) operated at an increasing return to scale. Gender, access to formal training, business registration, distance to the market and income from other sources significantly influenced the TE of candy enterprises. The study, therefore, recommends the need to develop strategies that can improve awareness and TE in baobab retailing. This includes; designing policies that promotes awareness and technical efficiency in the baobab sub-sector through training and educational programs. Similarly, gender-related issues should be addressed to bridge the gap of TE and awareness levels between female and male retailers. Likewise, county and national governments should invest in the baobab value chain and infrastructure to enhance access and availability of products in the markets. Hence, promote market development and commercialization of novel food products, particularly baobab.
Master of Science in Agricultural and Applied Economics
2024-03-28T00:00:00ZPerformance Characterization of a Thin-Film Photovoltaic System Powered Evaporative Charcoal Cooler for Preservation of Avocado (Persea americana Mill.)
http://localhost/xmlui/handle/123456789/6225
Performance Characterization of a Thin-Film Photovoltaic System Powered Evaporative Charcoal Cooler for Preservation of Avocado (Persea americana Mill.)
Langat, Victor Kiprotich
Avocados are high moisture content agricultural produce with high vitamin C levels. However, they are highly perishable, and suffer from high postharvest losses ifappropriate and adequate storage facilities are not provided. The losses noted with the use of conventional storage techniques, such as under shade, result from physical, chemical and physiological changes that result from loss in moisture content. This study aimed on characterizing the performance of a thin-film photovoltaic (PV) system powered evaporative charcoal cooler for preservation of avocado. Specifically, the study focused on characterizing the performance of the PV technology under varying ambient conditions as an off-grid backup energy system, evaluating the performance of an improved evaporative charcoal cooler utilizing the PV technology for preservation of avocado, and assessing the cost-benefit of using the improved evaporative charcoal cooler utilizing the PV technology for preservation of avocado. The evaporative cooler consisted of a double wire mesh that held charcoal in place and was fitted with a drip for wetting the charcoal-laden walls, axial fans and data logger with digital humidity-temperature sensors. The study was conducted in Kimicha (Kirinyaga County, Kenya) with an evaporative charcoal cooler to investigate the optimal tilt angle for thin-film PV, and also at Juja (Kiambu County, Kenya) for comparison purposes. The results revealed that the optimum tilt angle is 5o (347.9±231.9 W) in Kimicha and 15o (517.7±131.3 W) in Juja for average maximum solar radiation of 973.5±219.9 and 1086.4±211.41 W/m2 in Kimicha and Juja, respectively. No load tests using the cooler showed that a 0.5 m/s air velocity had the greatest drop in temperature, which was 6.4°C, and the highest cooling efficiency of 84.7%. The average temperature of the cooler decreased significantly (P < 0.05) for both Hass and indigenous avocado, while the relative humidity increased significantly (P < 0.05). These conditions gave mean cooling efficiencies of 83.0% for the Hass variety and 87.2% for the indigenous variety, and an energy efficiency ratio of 14.21 for the cooler. The study found that the Hass avocados experienced a 3.9 and 7.5% weight reduction in the cooler and outdoors, respectively, while indigenous avocados had a 5.03 and 12.90% weight reduction in the cooler and outdoors, respectively. No significant change in vitamin C content, total soluble solids and firmness of Hass and indigenous avocados was noticed. The benefit-cost ratio and return on investment for the cooler were 2.88 and 188%, respectively. These results suggest that investing in an evaporative charcoal cooler is a viable option for small-scale farmers.
Master of Science in Agricultural Processing Engineering
2024-01-29T00:00:00ZScreening of Beneficial Rhizospheric Bacterial and Fungal Isolates for Control of Bacterial Wilt of Tomato (Solanum lycopersicum L.) in Kenya
http://localhost/xmlui/handle/123456789/6218
Screening of Beneficial Rhizospheric Bacterial and Fungal Isolates for Control of Bacterial Wilt of Tomato (Solanum lycopersicum L.) in Kenya
Kones, Cheruiyot
Ralstonia solanacearum is a soil-borne pathogen causing bacterial wilt disease in solanaceae crops, including tomatoes. Available control strategies have been limited because of pathogen’s ability to develop resistance against pesticides, its wider host range, and ability to break host’s innate resistance. Management strategies including chemical and cultural practices have all failed causing the pathogen to be a threat to production. Although this pathogen is reported to result in 100% yield losses in the fields, pockets of uninfected plants are always visible. Little is known about the rhizosphere microbiome that would contribute to successful survival of plants amidst the highly virulent pathogen. In the current study, purposive sampling of rhizospheres from healthy tomatoes from Bomet, Kiambu, Kajiado and Kirinyaga was done. Pour plate method was used to screen for potential beneficial bacterial using nutrient agar media. Sprinkling method was used to screen for potential beneficial fungal isolates using potato dextrose agar amended with chloramphenicol at rate of 25mg/l. Purification of bacteria and fungi was done 48 hours and 72 hours, respectively, post incubation at 28 0C. Population of isolates revealed 40 bacterial isolates distributed as Bomet (48%)>Kiambu (27%)>Kajiado (18%) >Kirinyaga (8%). Similarly, fungal isolates were distributed as Bomet (30%)>Kiambu (28%)> Kajiado (23)>Kirinyaga (19%). Biochemical, microscopic and morphological characterization for bacterial isolates revealed Bacillus sp. (27.5%), Micrococcus sp., (27.5%) and Burkholderia sp., (15%) as the most dominant bacterial organisms inhabiting the rhizosphere of healthy plants. Macroscopic and microscopic description of fungal isolates also identified Aspergillus, Trichoderma, and Fusarium species as the most dominant fungal isolates in the rhizospheres of healthy tomatoes. Hierarchical cluster analysis done using DARwin software V6 clustered fungal and bacterial isolates into four and three clusters respectively. Finally, greenhouse experiments studied the efficacy of four bacterial isolates prequalified in the lab bioassays, in controlling bacterial wilt in Rio-grande tomatoes. Data on disease incidence, severity and population of R. solanacearum in roots and rhizosphere soils from each treatment revealed that both Bacillus sp. KMB16 and Pseudomonas sp.KJ2 significantly (p<0.05) reduced bacterial wilt incidence and severity on tomatoes. Further, treatments with the two antagonists resulted in a significant reduction of R. solanacearum in the roots of the tests plants. Bacillus sp.KJ4, Pseudomonas sp.KJ2, and Bacillus sp.BMT16 significantly (P<0.05) reduced population of R. solanacearum within the soil as compared to Burkolderia sp.KRN2. The result of this study contributes to knowledge of rhizosphere microbiome, diversity, and their potential. Further work needs to be done to formulate and utilize identified effective as an innovation that will shape the future of sustainable control of plant pathogens.
Master of Science in Horticulture
2024-01-24T00:00:00ZEvaluation of Portable Near-Infrared Spectrometer for Rapid and Non-Destructive Determination of Quality and Authenticity of Baobab (Adansonia Digitata l.) Fruit Pulp in Kenya
http://localhost/xmlui/handle/123456789/6212
Evaluation of Portable Near-Infrared Spectrometer for Rapid and Non-Destructive Determination of Quality and Authenticity of Baobab (Adansonia Digitata l.) Fruit Pulp in Kenya
Yegon, Denis Kimutai
The demand for baobab fruit pulp (BFP) is growing significantly due to increasing popularity of natural, organic, and nutritious ingredients. This demand has created the need for quality control to ensure quality and safety of the pulp. Conventional methods of assessing the quality of BFP are subject to human error, destructive and costly. Therefore, this study evaluated the ability of portable NIR spectrometer for rapid and non-destructive determination of key quality attributes of BFP. The study also evaluated the potential of the technique to monitor quality changes of stored BFP and to detect adulteration. A portable NIR spectrometer (Model: NIR-S-G1, Tellspec, Toronto, Canada) was used to acquire BFP spectra. Reference measurements on total titratable acidity (TTA), total soluble solids (TSS), vitamin C, and moisture content were immediately collected through specific wet-chemistry procedures. Chemometrics of partial least square regression (PLSR) was used to correlate between NIR spectra and reference measurements. Prediction model specific to each parameter was constructed and validated. This study proved that portable NIR spectrometer could be used for rapid, accurate, and non-destructive determination of BFP quality parameters with R2 of above 0.63 and RPD of above 2.00. A 23 factorial design storage experiment establishing the effect of storage duration (six months), storage conditions (25°C/75%RH and 35°C/83%RH), and packaging materials (unbleached kraft paper, UbKP and low-density polyethylene, LDPE) on quality of BFP. Constructed models were used to monitor changes in stored BFP. Additionally, microbial safety of stored pulp (total aerobic counts, TAC and total yeast and mold counts, TYMC) was determined through specific wet-chemistry procedures. Results indicated that the nutrient composition of stored BFP deteriorated regardless of the effect of packaging material and the storage conditions used. The TTA declined insignificantly (P>0.05) while TSS and vitamin C significantly reduced (P<0.05) at the end of the storage period. The moisture content of stored samples also increased significantly regardless of the protection offered by the packaging material. There was a significant growth of TAC over time (P>0.05) in all samples regardless of packaging and storage conditions. Yeast and molds were not detected in samples kept in LDPE bags until the end of storage. However, the increase in moisture content and microbial load of stored pulp did not surpass the upper limits stipulated by KEBS. Finally, the potential of portable NIR spectrometer to detect and quantify the adulterants in BFP was evaluated. Partial Least Square Discriminant Analysis (PLS-DA) was adopted for classification purpose. The device was sensitive and precise in the discrimination of pure and adulterated BFP. It detected rice, wheat, and maize fours adulterants with sensitivity and specificity of above 0.982 and error of below 0.009 for all two-class PLS-DA models. Finally, the PLSR was also used to establish predictive modes for quantifying the amount of adulterants present in BFP. The models proved to be efficient with prediction R2 and RMSE of above 0.88 and below 6.20% respectively. The models also resulted in reasonably low limits of detection (LODs) of 8.79%, 11.01%, 13.79% for rice, wheat and maize flours, respectively. Therefore, portable NIR spectrometer paired with chemometrics could be used for rapid, non-destructive, and cost-effective quality assessment of BFP. The adoption of portable NIR spectrometers by baobab value chain actors could help reduce post-harvest losses by enabling rapid, non-destructive quality screening of fruits to identify and reject immature or poor-quality batches. Furthermore, this cost-effective technique could be utilized to monitor changes in stored BFP, and rapidly screen for adulteration, thereby maintaining product authenticity and quality.
Master of Science in Food Science and Technology
2023-11-27T00:00:00Z